1. Field of the Invention
This invention relates to a device for Raman spectroscopy, which has a surface recess-protrusion structure. This invention also relates to a Raman spectroscopic apparatus, in which the device for Raman spectroscopy is utilized.
2. Description of the Related Art
Raman spectroscopy is a technique, wherein scattered light, which is obtained from irradiation of single-wavelength light to a substance, is separated into spectral components of the scattered light, and wherein a spectrum (i.e., a Raman spectrum) of Raman scattered light is thereby obtained. The Raman spectroscopy is utilized for identification of a substance, and the like. The Raman scattered light is weak light. However, it has been known that, in cases where light is irradiated to a substance in a state in which the substance is in contact with a metal body, particularly a metal body having a surface provided with fine recesses and protrusions, the intensity of the Raman scattered light is boosted.
As devices for Raman spectroscopy, which have a light scattering surface for scattering incident light, there have heretofore been known (1) a device for Raman spectroscopy comprising a metal body, whose surface has been electro-chemically roughed at random by the utilization of oxidation-reduction reactions, or the like, and (2) a device for Raman spectroscopy, comprising a metal body having a surface, to which fine metal particles have been fixed at random. (The aforesaid devices for Raman spectroscopy described under (1) and (2) are described in, for example, U.S. Pat. No. 5,376,556.)
Also, there has heretofore been known (3) a device for Raman spectroscopy comprising a metal body having a surface, to which metal-coated fine particles have been fixed regularly. The aforesaid device for Raman spectroscopy described under (3) maybe produced with a process comprising the steps of: forming a particle layer, which is provided with periodically arrayed fine particles of silica, or the like, on a base plate, introducing the base plate provided with the particle layer into a solution containing a metal and a polymer, taking the base plate provided with the particle layer out of the solution, drying the base plate provided with the particle layer, and firing the particle layer at a temperature, at which the polymer is capable of being burned out and at which the metal is capable of being fixed to the fine particles without agglomerating, the metal-coated fine particles being thereby fixed to the base plate. (The aforesaid device for Raman spectroscopy described under (3) and the aforesaid process for producing the device for Raman spectroscopy are described in, for example, Japanese Unexamined Patent Publication No. 2004-170334.)
However, with the aforesaid conventional techniques described under (1) and (2), which are described in, for example, U.S. Pat. No. 5,376,556, the problems are encountered in that, since the surface recesses and protrusions are formed at random, intra-plane non-uniformity occurs with the Raman scattering intensity. Therefore, detection of the Raman scattered light is not capable of being kept reliable, and high-accuracy measurements are not always capable of being performed reliably.
With the aforesaid conventional techniques described under (3), which are described in, for example, Japanese Unexamined Patent Publication No. 2004-170334, the metal-coated fine particles are regularly fixed to the surface of the base plate, and therefore the problems described above are capable of being eliminated. However, it is not always possible to perform each of the steps of: (a) forming the particle layer, which is provided with periodically arrayed fine particles having a size of a nano-order, or the like, on the base plate, (b) introducing the base plate provided with the particle layer into the solution containing the metal and the polymer, and taking the base plate provided with the particle layer out of the solution, such that the array of the fine particles, which have not been fixed to the base plate, may be kept, and (c) controlling the firing of the particle layer, burning out the polymer, and fixing the metal to the fine particles, such that the metal may not agglomerate. Therefore, with the aforesaid conventional techniques described under (3), which are described in, for example, Japanese Unexamined Patent Publication No. 2004-170334, the process for producing the device for Raman spectroscopy is not capable of being kept simple.